The article argues that important features of Luther's theology were shaped under the threat of excommunication. It is thus misleading to exclusively reconstruct theology of iustification in terms of individual salvation and inner conscience. His theology sheds light on legal exclusion and inclusion, on the limits of ecclesiastical authority and power, and entails dimensions of Political Theology. When Luther turned the tables in December 1520, by officially excommunicating the Pope, religious certainty was set on stage in a new way: a performance undermining sovereignty transforms the public understanding of the legal sphere.